Mechanistic insights into improved foaming and microbial safety of liquid egg white: The role of microwave, ultrasound, and pectin during cold storage.

Liquid egg white (LEW) is widely used in foaming dependent food systems, yet maintaining functional and microbial quality during cold storage remains challenging. In this study, microwave (MW, 300 W), ultrasound (US, 600 W) and pectin were applied to LEW. To establish industrial relevance, all treated and control samples were subjected to standard thermal pasteurization (57 °C for 3 min) before being evaluated during cold storge (4 °C, 35 days). Foaming capacity (FC) and stability (FS), ζ-potential, particle size, surface hydrophobicity (Ho), and total volatile basic nitrogen (TVB-N) were monitored every 7 days, while microbial safety was assessed by total colony count (TCC). All samples showed significant (P < 0.05) deterioration in foaming and quality indices with storage; however, the combined treatment (M300-U600-P) consistently exhibited the greatest functional retention. Specifically, untreated LEW FC decreased from 137.7 ± 5.0% to 85.5 ± 2.93% whereas M300-U600-P maintained significantly (P < 0.05) higher FC from 253.33 ± 3.3% to 222.2 ± 6.93% at day 35. Improved foaming performance was associated with enhanced electrostatic repulsion (higher absolute ζ-potential), aggregation control (regulated particle size), and altered interfacial protein behavior (modified Ho), which stabilized foam films and delayed storage induced quality deterioration. Based on the National Food Safety Standard of China for Egg and Egg Products (GB 2749-2015) regulatory TCC safety limit (3 × 104 CFU/mL), untreated EW exhibited an approximated shelf life of 24 days, while M300-U600-P extended shelf life to about 33 days. Overall, these findings support an emerging processing approach for the development of high-quality liquid egg products with extended shelf life.